// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/mac/os_crash_dumps.h"

#include <signal.h>
#include <stddef.h>
#include <unistd.h>

#include "base/logging.h"
#include "base/macros.h"

namespace base {
namespace mac {

    namespace {

        void ExitSignalHandler(int sig)
        {
            // A call to exit() can call atexit() handlers.  If we SIGSEGV due
            // to a corrupt heap, and if we have an atexit handler that
            // allocates or frees memory, we are in trouble if we do not _exit.
            _exit(128 + sig);
        }

    } // namespace

    void DisableOSCrashDumps()
    {
        // These are the POSIX signals corresponding to the Mach exceptions that
        // Apple Crash Reporter handles.  See ux_exception() in xnu's
        // bsd/uxkern/ux_exception.c and machine_exception() in xnu's
        // bsd/dev/*/unix_signal.c.
        const int signals_to_intercept[] = {
            // Hardware faults
            SIGILL, // EXC_BAD_INSTRUCTION
            SIGTRAP, // EXC_BREAKPOINT
            SIGFPE, // EXC_ARITHMETIC
            SIGBUS, // EXC_BAD_ACCESS
            SIGSEGV, // EXC_BAD_ACCESS
            // Not a hardware fault
            SIGABRT
        };

        // For all these signals, just wire things up so we exit immediately.
        for (size_t i = 0; i < arraysize(signals_to_intercept); ++i) {
            struct sigaction act = {};
            act.sa_handler = ExitSignalHandler;

            // It is better to allow the signal handler to run on the stack
            // registered with sigaltstack(), if one is present.
            act.sa_flags = SA_ONSTACK;

            if (sigemptyset(&act.sa_mask) != 0)
                DPLOG(FATAL) << "sigemptyset() failed";
            if (sigaction(signals_to_intercept[i], &act, NULL) != 0)
                DPLOG(FATAL) << "sigaction() failed";
        }
    }

} // namespace mac
} // namespace base
